People from Earth have landed on Moonbase Alpha, promising to take the Alphans back home. Commander Koenig, however, sees not fellow human beings, but aliens, and tries to kill some of them. Horrified, Helena stuns him with a laser gun and later, as he lies unconscious in the Medical Center, Koenig is approached by one of the aliens (for that is what they really are) who tries to smother him... ITC summary

The alien ship was built by Martin Bower with projecting panels like the alien ships in UFO. Only the side facing the camera was built. It was a late addition to the script (Johnson and Bower only had one day's notice that the model was needed).

On the underside of the pilot ship the top of an Airfix Eagle leg pod can just be seen

Stock footage of New York is seen (sc 119)

There seem to be just 3 sculpted alien "blobs"- where more appear, full-sized photo cut outs are used. (thanks to Patrick Zimmerman for spotting this!)

White noise is like white light, all frequencies heard together. It is commonly used for relaxing. It is not ultrasonic or anaesthetic.

Contact gases affect on skin contact; they do not need to be inhaled. Helena would be affected herself. Any air circulation system needs to have filters and protections to prevent, for instance, the spread of infection- here Helena is able to override or disable the atmosphere controls for the entire moonbase with a single, simple alteration.

A human brain runs on 4 watts, which is considerably less than the lights and other electrical equipment in Moonbase Alpha.

Intense radiation is ionising and causes genetic damage. In addition, explosions have a tendency to tear up and scatter cells in an often violent manner. If they need intense radiation, they should fly closer to a star. It seems unlikely any complex organism could withstand such treatment. How do they build a spaceship with such little kinetic energy?

"We've been in space for months. In Earth time that's generations. If they are from Earth, they'd have to be hundreds of years older than they appear." Time dilation is due to relative velocity (the Moon is moving faster than the Earth) and gravity. Koenig implies the Moon has been moving at a high proportion of the speed of light (like the Superswift). It ignores the space warps that the Moon has been through (and time warps). The Superswift could have left a few years after the Breakaway and matched the speed of the Moon, so the net time difference would be small. The difference on returning to Earth, for both the Alphans and the Superswift crew, would be larger. Thanks to Fergus.

There is a spacecraft flight path over lower Manhattan. On the other hand, this is all an illusion which need not be realistic.

New York as seen in the episode

The real New York in 1999.

The World Trade Centre towers (finished in 1977, destroyed 2001), Battery Park and 1 New York Plaza (the black building) are the most prominent features in these shots. The aerial shot was probably taken in early to mid 1972. The Bankers Trust building (later the Deutsche Bank Building) at 130 Liberty Street in front of the towers has a yellow stripe near the top. The upper levels were still being built when this film was taken (it would open in 1974; it was badly damaged in 2001 and demolished by 2011). Fortunately more recent developments such as the World Financial Centre and Battery Park City are not visible.

The ending, with Koenig fighting Alan as he tries to insert the nuclear fuel rod, is replayed in the climax of the 1999 James Bond film "The World Is Not Enough". James Bond tries to stop the villain putting a fuel rod into a submarine reactor and causing a nuclear explosion. Unlike Alan, the villain does not survive...